KR100331452B1 - Method for forming phosphor screen decreasing residual carbon compound - Google Patents

Abstract

The present invention effectively removes residual organic substances that cause residual gas through low-temperature firing processes when a phosphor is applied by using a slurry method or when polyvinyl alcohol or an acrylic emulsion is used to raise an aluminum reflective film. The fluorescent screen formation method which can be described is described. The phosphor screen forming method for reducing residual organic matter according to the present invention is a compound having an oxygen double bond structure such as ammonium peroxydisulfate ((NH ₄ ) ₂ S ₂ O ₈ ) in the process of producing a fluorescent film using polyvinyl alcohol A pyrolysis accelerator or a flammable perchloric acid (NH ₄ ClO ₄ ) or a carbon compound, such as C _n H _{2n + 1} (15 ≧ _n ≧ 10), is used in admixture with ammonium oxalate.

Polyvinyl alcohol is used by adding the above material to a mixture of polyvinyl alcohol and acrylic emulsion, which is used to increase the smoothness of the fluorescent film when slurry suspension such as phosphor and polyvinyl alcohol for phosphor screen production or aluminum protective film is deposited. By sufficiently removing even in the temperature range of 400 ° C., it is possible to easily reduce the luminance caused by the oxidation reaction caused by the high temperature firing of the phosphor and the organic substances causing the residual gas.

Description

Method for forming phosphor screen decreasing residual carbon compound

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a phosphor screen, and in particular, when a phosphor is applied by a slurry method or when a polyvinyl alcohol or an acrylic emulsion is used as a component of a peeling liquid used to raise an aluminum reflective film. The present invention relates to a method for forming a phosphor screen capable of effectively removing residual organic substances other than phosphors, which cause residual gas, through a low-temperature firing process so that the luminance of phosphors does not decrease.

In order to manufacture a cathode ray tube or a field emission type display using a phosphor, a method of applying a phosphor to a screen is required. Such a fluorescent screen may be prepared by dispersing a phosphor in polyvinyl alcohol, mixing a photosensitive agent, forming a phosphor line by ultraviolet exposure, and baking at 450 ° C. to remove polymer and organic components. 5,290,648) A method of dispersing a phosphor by isopropyl alcohol and the like and dissolving and mixing materials such as aluminum nitrate and magnesium nitrate to have a charge on the surface of the phosphor, and then dispersing the phosphor by electrophoresis under electric field. And a method of preparing a screen by printing after dispersing in acetate and nitrocellulose solution. In forming such a phosphor screen, different organic mediums are used to form a phosphor pattern, and organic matter is removed according to an appropriate firing method. If the residual organics are not completely removed, methane, carbon monoxide, carbon dioxide or other organic substances are generated in the vacuum due to the impact of electron beams or other photo- and thermochemical effects during electron beam irradiation. It reduces electron beam emission and generates arcs by vacuum discharge lamps, which shortens the life of the display.

The phosphor slurry process is performed in the order of "mixing-> coating solution-coating-> exposure-> green coating-> exposure-> developing-> baking. At this time, the components of the phosphor suspension mixture are composed of phosphor, polyvinyl alcohol, surfactant, antifoaming agent, dispersant, ammonium dichromate, distilled water, surfactant, antifoaming agent, dispersant, ammonium dichromate, distilled water, etc. Is mostly removed by evaporation at 200 ~ 350 ℃, but polyvinyl alcohol (PVA) starts to decompose at about 250 ℃ and does not completely decompose at 450 ℃. When the aluminum film is applied to increase the brightness of the phosphor screen after the phosphor screen is formed by the above method, the height of the phosphor film is changed. Therefore, polyvinyl alcohol is applied before heating and evaporating aluminum in vacuum to improve the smoothness. , A filming solution made of an acrylic emulsion solution and ammonium oxalate in the form of an aqueous solution was applied on a fluorescent film and aluminum was deposited thereon (see US 5,344,353, US 5,717,032). At this time, polyvinyl alcohol is used as one of the components of the peeling liquid used, and since it is necessary to completely remove aluminum after deposition, it is calcined and removed at 450 ° C. In this case as well, residual organic matter may be released into the vacuum display as a gas by the impact of the electron beam, and thus should be sufficiently removed. Alternatively, lacquers may be used as the peeling liquid (see US 5,556,664). In this case, due to the volatility of the lacquers, attention should be paid to process stability and exhaust.

As described above, in the case of manufacturing using organic materials such as polyvinyl alcohol used for applying the fluorescent film by slurry method or polyvinyl alcohol and acrylic emulsion used for depositing the aluminum protective film, the aluminum film is coated by increasing the smoothness of the phosphor. If the organic material introduced during screen formation is not sufficiently removed, this causes residual carbon to exist on the surface of the phosphor to reduce electron beam emission or to be coated on the phosphor, thereby reducing the emission of the phosphor. When firing at a high temperature of 450-500 ° C. to completely remove residual organic matter, performance degradation occurs due to the oxidation of phosphors. FIG. 1 is a graph showing the luminance of phosphors according to firing temperature, and shows a decrease in luminance of phosphors at high temperature firing at 450-500 ° C.

In order to achieve the above object, the present invention provides a method of manufacturing a screen by dispersing a phosphor in polyvinyl alcohol, and a method of forming a phosphor screen, and applying an aluminum film after forming the phosphor screen to improve the reflectance of the phosphor. The carbon pollutant is removed to reduce the generation of residual gas by removing organic substances such as polyvinyl alcohol remaining in the use of the filming solution used in the manufacture of the increased protective film. Reducing the generation of residual gas prevents the reduction of electron beam generation due to carbon contamination of the electron-emitting device, and provides a method of forming a phosphor screen that increases display life and performance by increasing luminance by firing the phosphor at a lower temperature. have.

1 is a graph showing the luminance of the fluorescent film according to the firing temperature in the manufacture of the phosphor screen,

2 is a structural formula of ammonium peroxydisulfate as a pyrolysis accelerator used in the phosphor screen forming method according to the present invention,

And Figure 3 is a graph for comparing the content of residual organic matter during firing by the conventional phosphor screen forming method and the content of residual organic matter during firing by the phosphor screen forming method according to the present invention.

In order to achieve the above object, the phosphor screen forming method according to the present invention is a compound having an oxygen double bond structure as a pyrolysis accelerator of the polyvinyl alcohol in a suspension mixture for producing a phosphor screen including a phosphor and an organic substance. Sulfate ((NH ₄ ) ₂ S ₂ O ₈ ) or flammable perchloric acid (NH ₄ ClO ₄ ) or carbon compounds, ie C _n H _{2n + 1} (15≥n≥10), C _n H _2n (15≥n≥ 10) mixing an ammonium oxalate and the like to form a phosphor film and then firing the phosphor film at a predetermined low temperature.

In the present invention, a polyvinyl alcohol as the organic material, 0.1-5% by weight of ammonium peroxydisulfate is mixed with 0.5-5% of ammonium oxalate as a thermal decomposition promoting compound having the oxygen double bond structure, or 0.1-5% by weight of ammonium perchlorate is mixed with 0.5-5% of ammonium oxalate, or 0.1-5% by weight of C _n H _{2n + 1} (15≥n≥10) is mixed with 0.5-5% of ammonium oxalate And a firing temperature of 400 ° C. or less, and to increase the smoothness of the phosphor film formed by the firing process, an organic compound mixture containing aluminum and polyvinyl alcohol is coated to form a fluorescent film protective layer, wherein the fluorescent film A thermal decomposition promoting compound having an oxygen polymerization structure is used in the organic liquid mixture for preparing the protective layer by mixing 0.1-5% by weight of ammonium peroxydisulfate with 0.5-5% of ammonium oxalate. Creating a layer preferably further includes the step of sintering the protective layer at a temperature not higher than 400 ℃.

Hereinafter, a phosphor screen forming method according to the present invention will be described in detail with reference to the drawings.

When the phosphor is mixed with a polyvinyl alcohol aqueous solution or the like and coated using a slurry method, which is a coating method through ultraviolet irradiation, or as a component of a filming solution used to form an aluminum reflective film on the phosphor film, polyvinyl alcohol or acryl In the case of using an emulsion, the organic substance is removed by heating and calcining after the film is applied. When calcining at about 450 ° C., polyvinyl alcohol and the like are present as about 3% of the remaining organic substance and residual gas is generated. It becomes a factor. In order to effectively remove the polyvinyl alcohol which is a source of residual gas, the present invention is mixed with a thermal decomposition accelerator to prepare a fluorescent film or a filming solution to use for forming a phosphor screen. That is, as a thermal decomposition accelerator, a compound having an oxygen double bond structure such as (NH ₄ ) ₂ S ₂ O ₈ (ammonium peroxydisulfate) or a combustible ammonium perchlorate (NH ₄ ClO ₄ ) or a carbon compound, that is, C _n H _2n 0.1-5 wt% of ₊₁ (15 ≧ n ≧ 10) is mixed with 0.5-5% of ammonium oxalate to form a phosphor turbid or a blooming liquid to form a phosphor screen. For example, ammonium peroxydisulfate, which is a thermal decomposition accelerator, is water-soluble and has good dispersion, and has a peroxite-structured oxygen polymerization (oxygen = oxygen) bond, which acts as a substance to promote decomposition when polyvinyl alcohol decomposition starts at 300 ° C. Allow sufficient removal even at ℃.

The detailed manufacturing process of the phosphor screen according to the present invention is as follows.

The phosphor is dissolved in an aqueous solution of polyvinyl alcohol and ammonium dichromate, an ultraviolet photosensitizer. Here, 0.1-5% of ammonium peroxydisulfate ((NH ₄ ) ₂ S ₂ O ₈ ) having a structural formula as shown in FIG. 2 is mixed with 0.5-5% of ammonium oxalate and stirred. After sufficient stirring, the coating is applied onto the conductive glass by spin coating, and then exposed to a suitable pattern and developed by applying water in a spray method. The glass substrate coated with phosphor is placed in a firing furnace and heated to 400 ° C., and then baked at 400 ° C. for 1 to 2 hours. At the time of firing, ammonium peroxydisulfate has high solubility in water and has a peroxide structure to promote thermal decomposition of polyvinyl alcohol, which maintains the phosphor film, thereby promoting decomposition of organic substances as a residual gas source and lowering the temperature at which thermal decomposition occurs. Luminance reduction is reduced. In addition, the ammonium oxalate added is needle-like crystals present in the polyvinyl alcohol film as needle-like crystals, and when calcined at a high temperature, the ammonium oxalate is contacted with oxygen to help the decomposition better by opening a hole between the films of the polyvinyl alcohol.

In addition, 0.5-5% of ammonium oxalate is added to 0.1-5% by weight of ammonium peroxydisulfate even when applying a mixture of polyvinyl alcohol and acrylic emulsion, which is used to increase the flatness of the fluorescent film when the aluminum protective film is deposited to increase the reflectance of the fluorescent film. Mixed with and coated on a fluorescent film, dried, and then heated to deposit aluminum. When aluminum is deposited, it is put in a baking furnace and heated up to 400 ° C., and then baked at 400 ° C. for 1 to 2 hours.

In the phosphor screen formed by this method, residual gas is reduced by the following principle.

In order to remove the filming mixture liquid, such as the polyvinyl alcohol used at the time of apply | coating a fluorescent film by the slurry method, the polyvinyl alcohol used at the time of aluminum vapor deposition, and an acrylic emulsion, it removes by heating at 450 degreeC for 40 minutes or more. Decomposition of polyvinyl alcohol starts at about 250 ° C or higher and must be heated to 500 ~ 550 ° C according to molecular weight or degree of polymerization to completely burn and remove carbon monoxide or carbon dioxide in the air. When the phosphor forming the phosphor film is exposed to a high temperature of 450 ° C. or above, the phosphor may react with oxygen in the air to deteriorate the fluorescence property, and thus the exposure to the high temperature should be avoided. In this case, the above-mentioned polyvinyl alcohol is not sufficiently removed. In this case, exposure to electron beams and heat causes photochemical or thermochemical reactions to generate residual gas present as carbon monoxide, carbon dioxide, or other carbon compounds, or to remain on the surface of the phosphor, resulting in deterioration of fluorescence. Therefore, in order to remove residual organic materials at low temperature in the process of manufacturing a fluorescent film by combining polyvinyl alcohol and another organic material, 0.1 to 5% by weight of ammonium peroxydisulfate is combusted while being soluble in water. Mixed with 0.5-5% ammonium or 0.1-5% by weight of ammonium perchlorate mixed with 0.5-5% of ammonium oxalate, or 0.1-5% by weight of C _n H _{2n + 1} (15≥n≥10) % Was used in combination with 0.5-5% of ammonium oxalate.

Ammonium peroxydisulfate is easily soluble in water and the decomposition of oxygen-oxygen bonds of peroxides is easy, so that decomposition starts at about 140 ° C. 0.5-5% of ammonium oxalate added is needle-like crystals present in the polyvinyl alcohol film as needle-like crystals, and when calcined at a high temperature, the polyvinyl alcohol film is sublimated to form holes in the polyvinyl alcohol film to help the decomposition to be better.

Alternatively, 0.1-5% by weight of ammonium perchlorate added is mixed with 0.5-5% of ammonium oxalate, or 0.1-5% by weight of C _n H _{2n + 1} (15≥n≥10) is mixed with 0.5-5% of ammonium oxalate. The mixture can also be mixed with polyvinyl alcohol to add flammability when combustion reactions occur at high temperatures, thus working well.

When ammonium peroxydisulfate is dispersed in an aqueous solution of polyvinyl alcohol in an appropriate amount to prepare a fluorescent film or when added to a filming solution used for an aluminum reflecting film, the thermal decomposition of the polyvinyl alcohol and organic compound mixture starts at about 300 ° C and is completed at 400 ° C. do.

0.1-5% by weight of ammonium peroxydisulfate is mixed with 0.5-5% of ammonium oxalate, or 0.1-5% by weight of ammonium perchlorate is mixed with 0.5-5% of ammonium oxalate, or C _n H _{2n + 1} (15≥n ≥10) In the case of a solution in which 0.1 to 5% by weight of ammonium oxalate is not mixed with 0.5 to 5%, decomposition proceeds to 300 to 550 ° C. Therefore, ammonium peroxydisulfate can be used to decompose organic matter at low temperatures and to reduce residual gas.

<Example 1>

50 grams of a 5% aqueous polyvinyl alcohol solution is mixed with 5 [g] of 5% aqueous ammonium dichromate solution and 2 [g] of 5% aqueous ammonium oxalate solution. A green (zinc sulfide: copper, aluminum) phosphor is added by adding 40 [g], and then coated on a glass coated with indium tin oxide with a spin coater. The fluorescent film is dried, exposed to ultraviolet light, and developed with water to form a fluorescent film pattern. The phosphor-patterned glass was put in a firing furnace and heated to 430 ° C., and then fired at 430 ° C. for 1 hour.

Comparative Example 1

55 grams of a 5% aqueous polyvinyl alcohol solution was mixed as in Example 1, and 5 g of 2% aqueous ammonium dichromate solution was mixed thereto. 40 g of green (zinc sulfide: copper, aluminum) phosphor is added, mixed, and then coated on a glass coated with indium tin oxide using a spin coater. The fluorescent film is dried, exposed to ultraviolet light, and developed with water to form a fluorescent film pattern. The phosphor-patterned glass was put in a firing furnace and heated up to 450 ° C., and then fired at 450 ° C. for 40 minutes.

<Example 2>

A solution of 50 g of polyvinyl alcohol 3% aqueous solution, 45 g of acrylic emulsion solution, and 2.5 g of ammonium oxalate and 2.5 g of ammonium peroxydisulfate was applied by spin coater onto the fluorescent film glass in which baking was completed in Example 1 above. After drying, it is placed in an aluminum evaporator to deposit 1000 Å thick aluminum. After the aluminum deposition is completed, put in a firing furnace and heated up to 400 ℃ and baked at 400 ℃ for 1 hour.

Comparative Example 2

A solution in which 50 g of polyvinyl alcohol 3% aqueous solution, 45 g of acrylic emulsion solution, and 5 g of ammonium oxalate was mixed was coated on a fluorescent film glass in which baking was completed in Comparative Example 1 by a spin coater. After drying, it is placed in an aluminum evaporator to deposit 1000 Å thick aluminum. When the aluminum deposition is completed, put in a firing furnace and heated up to 450 ℃ and then baked for 40 minutes at 450 ℃.

<Example 3>

48 grams of a 5% aqueous solution of polyvinyl alcohol is mixed with 5 [g] of 5% aqueous ammonium perchlorate solution and 2 [g] of 5% aqueous ammonium oxalate solution. 40 [g] of green (zinc sulfide: copper, aluminum) phosphors are added, mixed, and then coated on a glass coated with indium tin oxide by a spin coater. The fluorescent film is dried, exposed to ultraviolet light, and developed with water to form a fluorescent film pattern. The phosphor-patterned glass was put into a firing furnace and heated to 400 ° C., and then fired at 400 ° C. for 1 hour.

<Example 4>

48 g of 5% aqueous polyvinyl alcohol solution is mixed with 2 g of hexadecane and 2 [g] of 5% aqueous ammonium oxalate solution. 40 [g] of green (zinc sulfide: copper, aluminum) phosphors are added, mixed, and then coated on a glass coated with indium tin oxide with a spin coater. The fluorescent film is dried, exposed to ultraviolet light, and developed with water to form a fluorescent film pattern. The phosphor-patterned glass was put into a firing furnace and heated to 400 ° C., and then fired at 400 ° C. for 1 hour.

The completed phosphor screen was examined for surface carbon content by OJ electron analysis. The surface carbon content investigated is as follows.

Carbon / Total Amount Existed (%) Comparative Example 1 25.50 Example 1 10.30 Comparative Example 2 15.00 Example 2 8.50

As described above, the phosphor screen formation method for reducing residual organic matter according to the present invention is an oxygen polymerization such as ammonium peroxydisulfate ((NH ₄ ) ₂ S ₂ O ₈ ) in the process of producing a fluorescent film using polyvinyl alcohol. Suspension or aluminum for the production of phosphor screens by mixing pyrolysis accelerators or flammable perchloric acid (NH ₄ ClO ₄ ) or carbon compounds, such as C _n H _{2n + 1} (15≥n≥10), with ammonium oxalate When the protective film is deposited, it is added to a mixture of polyvinyl alcohol and acrylic emulsion, which is used to increase the smoothness of the fluorescent film, and the poly`vinyl alcohol is sufficiently removed even in the temperature range of 350 to 400 ° C. It is possible to reduce the decrease in luminance and to easily remove organic substances that cause residual gas. The residual gas affects the durability of the display by reducing it can extend the life and reduce the decrease in the electron emission characteristics of the electron beam emitting source. There is also an energy and process time saving effect to increase the temperature during high temperature firing.

Claims (9)

In the suspension mixture for producing a phosphor screen containing a phosphor and an organic substance, an ammonium peroxydisulfate compound having an oxygen double bond structure as a pyrolysis accelerator of the polyvinyl alcohol and acicular crystals are present in the polyvinyl alcohol film as acicular crystals and then sublimed at high temperature. And forming a phosphor film by adding ammonium oxalate, which helps to decompose by contacting with oxygen by making a hole between the films of polyvinyl alcohol, and then calcining the phosphor film at a predetermined low temperature. Phosphor screen forming method for reducing residual organics. The method of claim 1, And a polyvinyl alcohol as the organic material, and using ammonium perchlorate, which is a combustible material, as a pyrolysis-promoting compound having an oxygen double bond structure, and mixed with ammonium oxalate. The method of claim 1, Residuals comprising polyvinyl alcohol as the organic material and using a combustible material C _n H _{2n + 1} (15≥n≥10) mixed with ammonium oxalate as a thermal decomposition promoting compound having an oxygen double bond structure Phosphor screen formation method for organic matter reduction. The method of claim 1, The ammonium peroxy disulfate is 0.1 to 5% by weight of phosphor screen formation method for reducing residual organic material, characterized in that mixed with 0.5 to 5% by weight of ammonium oxalate. The method of claim 1, Residual organic material comprising polyvinyl alcohol as the organic material, and 0.1-5% by weight of ammonium perchlorate as a combustible material is mixed with 0.5-5% by weight of ammonium oxalate as a thermal decomposition promoting compound having an oxygen double bond structure. Phosphor Screen Formation Method for Reduction. The method of claim 1, 0.1-5 wt% of ammonium oxalate with 0.15 wt% of C _n H _{2n + 1} (15 ≧ _n ≧ 10), which is a combustible material, as a thermal decomposition promoting compound having polyvinyl alcohol as the organic material and having the oxygen double bond structure Method for forming a phosphor screen for reducing residual organic material, characterized in that used in combination with. The method according to claim 1 or 2, The firing temperature is 400 ℃ or less method for forming a phosphor screen for reducing residual organic material. The method of claim 1, In order to increase the smoothness of the phosphor film formed by the firing process, an organic compound mixture containing aluminum and polyvinyl alcohol is applied to form a fluorescent film protective layer, and a thermal decomposition promoting compound having an oxygen polymerization structure in the organic material mixture for preparing the fluorescent film protective layer. As ammonium peroxydisulfate and acicular crystals, ammonium oxalate is present in the polyvinyl alcohol film as acicular crystals, and when calcined at high temperature, it is sublimed and pierces the membrane of the polyvinyl alcohol to contact oxygen with oxygen to help the decomposition better. Adding to form a protective layer and calcining the protective layer at a temperature of 400 ° C. or lower. The method of claim 8, Method for forming a phosphor screen for reducing residual organic material, characterized in that the mixture is used by mixing 0.1 to 5% by weight of ammonium peroxydisulfate and 0.5 to 5% by weight of ammonium oxalate as the thermal decomposition promoting compound.